Human skin color is determined by a lot of factors including activity of melanin-producing melanocytes, distribution of blood vessels, skin thickness, and presence of pigments such as carotenoids, bilirubin, etc. Above all, skin color is determined primarily by the black pigment melanin produced by melanocytes through the action of tyrosinase and other enzymes. The production of melanin is affected by genetic factors, physiological factors such as hormones and stress, and environmental factors such as UV. Existing in skin, melanin protects the skin from UV or the like. But, overly produced melanin is known to accelerate pigmentation and skin aging and to play an important role in skin cancer. In order to treat or ameliorate abnormal or excessive melanin pigmentation caused by exposure to UV or the like, ascorbic acid, kojic acid, arbutin, hydroquinone, glutathione, derivatives thereof or tyrosinase-inhibiting substances have been added to cosmetics or medicines. However, their use is restricted because of insufficient skin whitening effect, skin safety issue, stability when added to cosmetics, or the like.